Method for neutralizing obnoxious radiation



Nov. 22, 1960 R. ALBERTI ,9

' METHOD FOR NEUTRALIZING OBNOXIOUS RADIATION Filed Sept. 30, 1957 I v INVENT'OP Rua/aIfALBERTI METHOD FOR NEUTRALIZING OBNOXIOUS RADIATION Rudolf Klberti, 'Waschegrund 461, St. Andreasberg, "Germany ,Eiled Sept. 30, 1957,,Ser. ;No.,-68'Z,3.16

"Claims priority, application Germany Oct. "1, 1956 4! Claims. (Cl..:210,24)

;Ihe -,pr,esent invention relates :to a method :and tapparatus :.f or gneutralizing ,or eliminating radioactive .iso- :;topic ,waste.

One of the ;most important problems ;:of modern. science and zindustry concerned with :radioactive :materials :as useddn ;zatomic reactors, scientific laboratories, hospitals, and .various tother places is .the elimination :of the -..waste of ;such -materials which is .still .sufiiciently radioactive to .for m a source ofvdanger. .Although'there have been -various proposals rdealing =Wi'th -the iquestionsmf decon- --;tamina ti-ngtwater Which'has become infected :with radio active matter, and of storing, transporting and finally eliminating ;the atomic waste, these proposed methods are :still quiteginadequate and largely 'very .uneconomical. ;Barticularly ;f or eliminating the radioactiveiisotopic .waste water and other waste .xsubstances accumulating a'lll laboratories and hospitals, ,where the -many :smaller indivi- ;,du a l amounts of such substances .are produced at dififerent times andpointstmightby themselves .not'ibe regarded as really dangerous, there has -so far been no .proposalofiany method which is suitable iforelimin'ating -or decontaminating the :respective liquid or other sub- ;stanc es; at= s uch low :cost and also soeasily and safely, particularly iniview ofathe sfrequent carelessness o'f perrsons Working :with such I dangerous waste materials, that such method would be really practicable.

:lt'is the principal :object of the present invention to provide ,a new method which is simple and easily applicable {for :quickly .and effectively converting radioactive isotopic --Waste, and :particularly such waste as may "be contained j-in a dissolved or suspended state in watery 1iquids,:into:a-form in-Whichit may be handled, stored, transported, and finally and completely eliminated :more easily .andsimply, with :less danger, and at a lower cost than possible accordingzto the previous methods.

5 The present invention takes advantage of the Wellknown property of materials which have a high density and a specificgravity of more than 4 of being relatively impermeable to and shielding against radiation, and it consists "in a method of neutralizing radioactive isotopic waste or rendering the same harmless by applying materials of the-mentioned kind in a pulverized condition for absorbing finely distributed isotopic waste. The materials which 'are especially suitable for this purpose are, :for example, .heavy metals and/or their compounds, lead, barium compounds, heavy spar, finely ground lead .ores and iron ores, ferrous minerals, magnetite, iron dust, :lead dust, galena, cinnabar,and bismuth compounds such as for example, the finely pulverized bismutum 'subnitricum and the like used for pharmaceutical purposes. 65 Sludge consisting 90% of Baso and .Even pulverized slag containing heavy-metal oxides and therefore of a relatively high specific gravity may be usedfor this ,purpose. Avery inexpensive absorbing material which is very suitable for the purposes of the yinventionjs finely pulverized barite, especially also in the form ofa-dried sediment -or sludge such as accumulates .in largelguant-itiesrin baritetupgrading and refining plants,

2,961,399 Patented Nov. 22, 19 0 10 powder, the protection attainable'in alldirections bya certain amount of pulverized 'baritezor the 1ike-may be rea'lize'd .zmueh more economically if -it would be applied directly and-within the volume of the respective liquid rather than if the sameamount of barite is used, for ex- .ample, in the-form of masonry for screening ofi the-en- "tire radiation of the unmixed liquid. Calculation and experiments showthat'for attaining a certain degree 10f protection in all directions by means of -barite, "the amount of this material, applied in'the formof screening 0 Walls aroundthe liquid containing the isotopic Waste "will "have to be three to four times as much as-if-it is used 'aecordingto the invention in a finely pulverized form 'fordirectly absorbing the radio-active liquid. The'allaround a protection attainable according 1 to the invention is 5 therefore not only 'applied more easily and economically bu-t it is also much more eifective.

The method according to the invention maybe applied, for example, for the purpose of neutralizing, removing, and storing radioactive "sewage and waste "Water of any kind, for instance, from atomic reactors. This-method may be'carried out, for example, in a pcol method in Which-the collectedwaste water is mixed with-a sufiicient quantity of a barite sludge to absorb the water. 'By grinding suchsludge by-means of iron balls to-a degree of fineness of, for-example, -80 to 90% below '2 it is possible to increase its absorptive capacity'to such an extent -that, for examp'le, 'an amount of 10 to 20 tons 10f barite sludge :will be-entirely sufficient for safely storing a quantity of 9000-liters of waste water, which accumu- 40 slateseachday from the operation-of an atomic reactor,

-until:the short lived radiationof-this Water which is especiallysdangerous has faded away. The high barite con- -1tent reduces the radiation of the absorbed radioactive liquid 'to:a-considerably greater extentthan if it is mixed,

ifor :example, only with 'argillaceous substances which .might lbe added to facilitate its handling. Since the rbarite vsludge :also does not-combine with the Water as ."firmly :as .argillaceous substances, but primarily by sur- :face absorption, such =sludge saturated with the isotopic 0 Eliquid may again be-dried-much more easily and without :dan-ger, tor-example, 'after'the short-lived radiation has fadedoff after ;the 'materialhas been stored for'a'quarter to a half year, whereupon the same material may again .tbez-u'sed after the period of dangerous radiation has ex- :pired.

For determining the'amount of protection attainable by the methodaccordingtothe inventionas above described, =that-is, by absorbing :the radioactive liquid in a radiationabsorptive powder, 'the "following comparative experi- First the radiation .was measured which emanates from a certain .quantity .of a radioactive liquid. l'his liquid was then absorbed by a finely ground, dry barite radiation of the mixture of liquid and sludge amounted to only 31% of the radiation of the liquid alone.

The use of the radiation-resistant properties of the pulversized material, for example, magnetite or barite powder, which is intimately intermixed with the finely distributed isotopic matter may also be combined with the effect of other known materials which in the event that the isotopic waste is in a state of suspension, will filter out these suspended particles from the liquid or which in the event of radioactive ions being dissolved in the liquid, will remove these ions from the contaminated water by the action of ion exchangers, for example, that of argillaceous substances of a type similar to montmorillonite or of synthetic-resin ion exchangers. According to the present invention, the pulverized protective material, for example, finely pulversized barite, may also be used either alone or in combination with other filtering materials as a filling or filtering apparatus, trickling towers, or the like in which contaminate liquids are freed of isotopic waste particles which are suspended therein. Similarly it is possible to apply a finely pulverized protective material such as pulverized barite or the like in combination with ion exchangers of the mentioned kind as a charge for decontamination plants in which dissolved radioactive ions are to be removed from contaminated water. The amount of the additions of radiation-resistant materials to be contained in the filling materials of the filtering apparatus or ion-exchangers is limited in the upward direction by the maximum which does not as yet considerably impair the filtering or ionexchange effect and which may in each individual case be easily ascertained by experiment. For filtering purposes it is thus, for example, often possible to use a layer of pure barite of a suitable fine granular size. The lower limit in the amount of these additions is approximately that where a further increase in the radiationresistant effect can no longer be expected as seen from the standpoint of economy, required space, or expenditure as compared with a filtering or ion-exchange .material which does not contain any special radiation-resistant additions, that is, for example, at a content of 50% of barite in the absorptive layer.

The residue accumulating in the filtering or other decontamination apparatus may then be solidified in a manner known as such by baking the same in a kiln, to form a ceramic body or by means of hydraulic cementing' agents to form bodies which are of sufiicient strength to be transportable. barite or other materials which are deposited in these bodies then extensively screen off the radiation which tends to emanate from these bodies in all directions so that, for example, the handling and transporting of the clay columns which have been formed by being baked and which contain the isotopic matter can be carried out with considerably less danger than previously was possible.

Instead of enclosing the radioactive waste products in transport containers made of hydraulically hardening cement or the like which are then sunk into the sea, as was previously done, it is much more advantageous if, according to the invention, a mixture of finely ground dry barite powder, a pulverized iron oxide, or other heavy-metal mineral together with an amount of cement sutficient for setting the same is used for absorbing the liquid which is to be eliminated. The body which is thus formed of barite and cement may then have a barite content of, for example, 50 to 95%, since a cement content of as little as 5% or less is often sufficient to produce blocks which are sufiiciently solid to be transported. The upper and lower limits of the content in radiation resistant materials are determined by the same principle as previously stated with respect to the amount of such additions in filling materials for filters or ion exchangers. Due to its uniformly distributed contents in barite or other protective materials, the block thus The fine protective particles of produced will emit considerably less radiation than the cement blocks used up to the present time for sinking atomic waste products. Furthermore, their content in highly absorptive, finely ground barite also enables such blocks which are to be sunk to absorb a greater volume of contaminated liquid than the blocks previously used.

The present invention also permits the construction of combined decontamination apparatus or plants which, in a manner similar to drip filters, contain montmor1llonite, as well as barite sludge or pulverized heavymetal minerals to serve as filtering, absorptive, and ionexchange material.

At any rate, the sludge or solid bodies formed by the use of finely pulverized barite or similar material with the finely distributed isotopic matter absorbed therein may be stored with much less danger and requires less additional protective measures than the isotopic waste would require either by itself or when mixed with materials of a lower specific gravity than barite or other radiation-absorbent substances. During the time while the most dangerous short-lived radiation fades ofif to a strength below the danger point the ionizing rays, particularly the alpha, beta, and gamma rays are also extensively shielded from penetrating toward the outside. A further advantage of the use of the mentioned pulverized radiation-resistant materials, for example, barite powder, for absorbing the radioactive liquid, as compared with allowing such liquid to stand by itself until the radiation has faded off to a point below the danger limit, also consists in the fact that the danger will be fully prevented that the liquid might seep into the ground. Also, instead of allowing the radioactive waste to stand in lead containers, as is still frequently done, and then to drop such containers into the sea, it is also much safer and more convenient to collect the waste products in chambers which are filled with barite sludge or the like until the dangerous radioactivity has faded off. If it should then be necessary to transport the waste to a safe place because the radiation might continue to exist for a greater length of time, such transportation will also be much easier and less dangerous if the waste products are intimately mixed with the barite powder or the like and are thus diluted, as well as screened from the outside.

The degree of pulverization and the absorptive capacity of the materials, such as heavy minerals, barite, and the like used for absorbing the watery isotopic matter is preferably determined in each case by experiment in accordance with the particular screening effect required.

It is another object of the invention to apply the method according to the invention in laboratories or similar places in which radioactive liquids are used, and to provide suitable vessels which are filled with dry pulverized radiation-absorbent materials such as a fine barite powder and are kept quickly available so that in the event some of these radioactive liquids might be spilled or splashed, the protective material may be immediately poured over the source of danger and the radioactive liquid will thus be immediately absorbed by the barite or similar powder and may then be quickly and easily removed therewith. Consequently, it is no longer necessary to absorb or wipe oil? the dangerous liquid with rags which then have to be disposed of, or to flush it away with water which might reduce the concentration of the spilled radioactive substances but, in turn, might contaminate the sewage and would actually not fully eliminate the danger. Such vessels filled with radiation-absorbent powder, for example, barite powder, and provided with a cover and a bail or handle should be readily available at all points where radioactive liquids might possibly be spilled or splashed. For this purpose it has also been found very advisable to use a strongly colored absorbent powder such as, for example, the above-mentioned cinnabar, which when poured over the splashed radioactive liquid to absorb the same, will permit thedanger spot to remain con spicuous until it can soon thereafter.be removed entirely.

The fine'ly pulverizedbar'ite or thelike mayaccording tothe invention also be used in hospitals, either alone or .in combination with the usual absorptive materials such as ground peat, "for absorbing and removing feces which are radioactively contaminated. 1Such removal of the .dangerous matter after adding an adequate amount of radiation-absorbent powder thereto is much safer and .more complete-than themethods previously used.

A further important application'o'f the pulverized protective materials according to tthe'invention consists in their use as a cleansingmaterialffor cleaningand scrubof a baritesludge which consistsof the finest. ingredients attained in the upgrading oLrefining-ofbarite whichhave only a small clay content, forexamplaup to.2.% butcannot be utilized'for painting purposes. The basic material may also consist, for example, of .a purified .sludge accumulated from the process of washing the "barite and containing a slightly higher percentage in argillaceous ingredients. Suchsludge which is accumulatedin apools is then dugout therefrom and wet-ground intubular ball mills until it has attained a granular size of, for example, 90% below 2a. The mass is then dried and disintegrated, whereupon it is ready to be applied for the purposes according to the invention as above described. Residual or waste sludge may in some cases also be used as an addition to cement without being ground, and so-called refining sludge may in most cases be utilized directly, either with or without being additionally ground.

Further objects, features, and advantages of the present invention will appear from the following short description of suitable apparatus and appliances for neutralizing and eliminating radioactive isotopic waste, a few examples of which are illustrated in the accompanying drawings, in which Fig. 1 shows a bucketlike container for suitably holding the radiation-absorbent powder according to the invention;

Fig. 2 illustrates a small container similar to a sugar dispenser;

Fig. 3 illustrates diagrammatically an apparatus for decontaminating radioactively infected liquids;

Fig. 4 shows a solidified body of finely divided radiation-absorbent material according to the invention for storing or transporting the radioactive substances to be eliminated; while Fig. 5 illustrates a hydraulically-set block which largely consists of the protective material according to the invention.

Referring to the drawings, Fig. 1 illustrates a bucketlike container 1 of a handy size with a handle 2 and a cover 3, which is suitable for use in laboratories and the like in which isotopic substances are being used. The container is designed to hold a filling 4 of dry, finely pulverized barite or other suitable radiation-resistant powder. It should be kept in a quickly accessible place so that if some of the radioactive liquid used in the laboratory might be spilled or splashed, the dry powder can be quickly poured from the container over the spilled liquid so that the same will be immediately absorbed by the powder and may then be easily removed at any convenient time without danger.

Fig. 2 illustrates a glass jar 12 similar to a sugar or salt dispenser which is filled with cinnabar powder 14 and provided with a pouring lid 13 through which the powder lead sulphide, magnetite powder, or the like.

may be .easily Poured directly .npon asmall ,spots .of

radioactive liquid. The strong colorofthe absorptive powder makes the ,spots conspicuous and facilitates their complete removal whenever the attendant can interrupt .his work or after .he .has completed the same.

' ,Fig. 3 diagrammatically illustrates an apparatus for decontaminating radioactively infected liquids. It consists of a container 5 with afilter plate6 andalayer 7 resting thereon which consists of a filtering, absorbent,

.outlet 9.

Fig. 4 illustrates a solidified body 10 which has been removed from :a filter similar to that shown in Fig. 3

and may .be easily stored .or transported. ltwmay consist of clay, vfor example, of the group which includes ion-exchanging.montmorillonite, with anadequate content in finely ground radiation-resistant material of the type mentioned above which, afterbeing saturated with the .isotopic matter to .be eliminated, is baked in aceramic furnace'or kilnand is thussolidified. The content .in radiation-resistant materials of a high specific gravity .is preferably such that the density of the dry ceramic mixture is not lower than approximately 2.5.

Fig. 5 finally illustrates a hydraulically set block 11 which has a cement content of 10% and a remaining content of finely powdered barite or other radiationresistant material. If the radiation-resistant addition consists of barite, the block will have a specific gravity of 3.5 to 4, while when using magnetite, the specific gravity will be even higher. The water used for setting the cement may be the same as that which is absorbed by the barite or similar material, that is, the radioactively contaminated water which is to be neutralized or eliminated. Another preferred hydraulic mixture which first absorbs the radioactive liquid and then utilizes the same for setting the mixture consists of 70% by weight of dry, finely pulverized barite sludge with a content of in BaSO 20% by weight of cement, and

10% by weight of bentonite.

The density of the dry hydraulic mixtures should preferably be no less than 2.8.

The radiation-resistant materials, which according to the invention are to be applied in a pulverized condition either alone or in combination with other materials such as filtering materials, absorptive clay, hydraulic or other setting agents, or the like for the purpose of absorbing the finely distributed isotopic substances, may consist of the same materials which have already been used prior to this invention as radiation-resistant materials, particularly such materials with a specific gravity of at least 4. This primarily includes heavy minerals such as barite and heavy-metal compounds. Since such heavy mixtures often contain more or less amounts of lighter ingredients, for example, clay as contained in barite sludges, the dry mixture may be given a minimum density (not volumetric weight) of 3.5.

Although my invention has been described with reference to the preferred application of the finely pulverized materials for absorbing radioactive substances which are dissolved or suspended in liquids and for reducing the radiation thereof toward the outside, I wish to have it understood that it is in no way limited to such application and to the details thereof but is capable of numerous modifications within the scope of the appended claims and particularly to the use of these and similar materials in a finely divided form for separating, receiving, and absorbing such radioactive substances from flue and other gases in which they might be suspended.

Having thus fully described my invention, what I claim is:

1. A method of absorbing obnoxious radiation emitted by radioactive waste material contained in water which comprises inserting the water into a mixture of a pulverized radiation-absorbent material having a content of at least 50% of barites and having a further content of a hydraulic setting agent, absorbing said water including said radioactive waste material within said pulverized material, and also utilizing said Water for substantially solidifying said mixture by means of said setting agent.

2. A method of absorbing obnoxious radiation emitted by radioactive waste material contained in water which comprises passing the water with the waste material content into a mixture of a hydraulic setting agent and of between 50% and 95% powdered barite, and absorbing the water with said waste material within said powdered barite while also using the water for substantially solidifying said mixture by means of the setting agent.

3. A method of absorbing obnoxious radiation emitted by radioactive waste material contained in water which comprises passing the water including its waste material content into a mixture comprising a hydraulic setting agent, between 80% and 90% powdered barite, 90% of which at least is below 2 microns in diameter, and an argillaceous substance, and absorbing the water with said waste material within said powdered barite and said argillaceous substance while using the water for substantially solidifying said mixture by means of the setting agent.

4. A method of absorbing obnoxious radiation emitted by radioactive waste material contained in water which comprises passing the water with its waste material content into a mixture comprising by weight of dry, finely-pulverized barite with a content of at least in barium sulphate, 20% by Weight of cement, and 10% by Weight of bentonite, and absorbing the water including said waste material within the pulverized barite and the bentonite while using the water for substantially solidifying said mixture by means of the setting agent.

References Cited in the file of this patent UNITED STATES PATENTS 2,682,268 Ryan June 29, 1954 OTHER REFERENCES Bibliography of Solid Adsorbents, US. Dept. of Commerce, National Bureau of Standards Circular 566, page 1944, 5, No. 4549 (1955).

Engineering Bulletin, Proceeding on the Eighth Industrial Waste Conference May 4, 5 and 6, 1953, Purdue Univ. Series No. 83, January 1954, pages 480-5 espec. page 482.

Gallaher et Ritzes; Oak Ridge National Lab. (ORNL) 1414, Summary Report on Portland Cement US. Atomic Energy Commission Concretes For Shielding, Mar. 2, 1953.

Ginell Nov. 4, 1952 

1. A METHOD OF ABSORBING OBNOXIOUS RADIATION EMITTED BY RADIO ACTIVE WASTE MATERIAL CONTAINED IN WATER WHICH COMPRISES INSERTING THE WATER INTO A MIXTURE OF A PULVERIZED RADIATION-ABSORBENT MATERIAL HAVING A CONTENT OF AT LEAST 50% OF BARITES AND HAVING A FURTHER OF A HYDRAULIC SETTING AGENT, ABSORBING SAID WATER INCLUDING SAID RADIOACTIVE WASTE MATERIAL WITHIN SAID PULVERIZED MATERIAL, AND ALSO UTILIZING SAID WATER FOR SUBSTANTIALLY SOLIDIFYING SAID MIXTURE BY MEANS OF SAID SETTING AGENT. 